JP2010105440A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire suppressing intrusion of a bead part into a rim ring dividing position and deformation of a rim cushion. <P>SOLUTION: The pneumatic tire 1 includes a pair of bead cores 2 and a carcass layer 4 suspended between these bead cores 2. The ends of the carcass layer 4 are turned back outward in a tire width direction to envelop the bead cores 2. The pneumatic tire 1 also includes a carcass reinforcing layer 5 for reinforcing the carcass layer 4 disposed at turn-back portions of the carcass layer 4; and a rim cushion reinforcing layer 6 for reinforcing the rim cushion disposed in a region brought into contact with a rim flange in a rim assembly state of the tire. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that can suppress biting of a bead portion into a split position of a rim ring and deformation of a rim cushion portion.

  In recent pneumatic tires, a bead base portion has a reinforcing layer made of an organic fiber material in order to suppress deformation of the rim cushion portion. As a conventional pneumatic tire employing such a configuration, a technique described in Patent Document 1 is known.

JP 07-276930 A

  In general, the rim 10 to which a pneumatic tire is attached includes a rim body 11 and a rim ring 12, and a part of the rim body 11 and the rim ring 12 constitute left and right rim flange portions of the rim 10. (See FIG. 9). And the bead part of the tire 20 is assembled | attached to these rim flange parts, and the rim | limb assembly of a tire is performed.

  By the way, in a specific market, a rubber sheet may be inserted between the split position of the rim ring 12 and the bead part in order to suppress biting of the bead part into the split position of the rim ring 12. Then, when the load is applied, the distortion of the rim cushion portion increases, and the fitting state between the tire and the rim becomes uneven. In addition, there is a possibility that the riding comfort performance of the tire is lowered, and there is a possibility that a failure (separation of the rubber layer at the edge portion of the carcass layer or the reinforcing layer) may occur during traveling.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire that can suppress the bite portion from biting into the split position of the rim ring and the deformation of the rim cushion portion.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a pair of bead cores and a carcass layer bridged between the bead cores, and an end portion of the carcass layer is wound outward in the tire width direction. A pneumatic tire that is returned and wraps around the bead core, the carcass reinforcing layer that is disposed in the winding portion of the carcass layer and reinforces the carcass layer, and a region that contacts the rim flange portion in the rim assembled state of the tire It has a plurality of rim cushion reinforcement layers which are arranged and reinforce the rim cushion part.

  In this pneumatic tire, since the rim cushion reinforcing layer is disposed in a region that contacts the rim flange portion in the tire rim assembly state, the rim cushion portion is reinforced. In such a configuration, the bead portion is prevented from biting into the split position of the rim ring in the tire rim assembled state. As a result, there is no need to insert a rubber sheet between the split position of the rim ring and the bead portion, and there is an advantage that deformation of the rim cushion portion is effectively suppressed. For example, in a configuration in which a rubber sheet is inserted between the rim ring split position and the bead portion in order to suppress biting of the bead portion into the rim ring split position, the distortion of the rim cushion portion increases when a load is applied. The deformation of the rim cushion part tends to be excessive. In addition, since the carcass reinforcing layer and the rim cushion reinforcing layer are respectively disposed, the rim cushion portion is effectively reinforced. Thereby, there exists an advantage by which the deformation | transformation of a rim cushion part is suppressed effectively. Further, in this pneumatic tire, the rim cushion portion is effectively reinforced as compared with the configuration in which the rim cushion reinforcing layer has a single layer structure. Thereby, there exists an advantage by which the deformation | transformation of a rim cushion part is suppressed effectively.

  The pneumatic tire according to the present invention is made of a cord material in which the rim cushion reinforcement layers are arranged, and the plurality of rim cushion reinforcement layers are laminated with the fiber directions of the cord materials intersecting each other.

  In this pneumatic tire, the rigidity of the rim cushion reinforcing layer is increased as compared with a configuration in which the rim cushion reinforcing layer is laminated with the fiber direction of the cord material oriented in the same direction. Thereby, there exists an advantage by which the bite part bite into the split position of a rim ring is suppressed effectively.

  In the pneumatic tire according to the present invention, the fiber direction of the cord material of the laminated rim cushion reinforcement layer is inclined within a range of 0 [deg] or more and 40 [deg] or less with respect to the tire circumferential direction.

  In this pneumatic tire, the rigidity of the bead portion is increased by setting the inclination angle of the cord material to be low. Thereby, there exists an advantage which the durability of a bead part improves.

  Further, in the pneumatic tire according to the present invention, at least two rim cushion reinforcement layers on the outer side in the tire width direction among the plurality of laminated rim cushion reinforcement layers are made of an organic fiber material.

  This pneumatic tire has an advantage that the separation of the rubber material at the end of the rim cushion reinforcing layer is suppressed as compared with the configuration in which the rim cushion reinforcing layer on the outer side in the tire width direction is made of a steel fiber material.

  Further, the pneumatic tire according to the present invention has a cross section from the intersection B when the intersection B between the perpendicular drawn from the center of gravity of the bead core in the tire radial direction and the bead base portion is taken in a sectional view in the tire meridian direction. The distance H in the tire radial direction to the outer end in the tire radial direction of the rim cushion reinforcing layer and the distance RH from the intersection B to the rim and tire separation point when loaded are 1.0 ≦ H / RH ≦ 1. .5 relationship.

  In this pneumatic tire, since the positional relationship H / RH between the end of the rim cushion reinforcing layer on the outer side in the tire radial direction and the rim and the separation point of the tire is optimized, the split position of the rim ring in the tire rim assembly state There is an advantage that biting of the bead portion into the head is effectively suppressed.

  In the pneumatic tire according to the present invention, the end portion on the inner side in the tire radial direction of the rim cushion reinforcing layer is in the vicinity of the inner end portion in the tire radial direction of another reinforcing layer arranged in the bead portion.

  In this pneumatic tire, the position of the end portion of the rim cushion reinforcing layer on the inner side in the tire radial direction is optimized, so that the generation of cracks starting from the end portion on the inner side of the rim cushion reinforcing layer in the tire radial direction is suppressed. There are advantages.

  In the pneumatic tire according to the present invention, at least a pair of the rim cushion reinforcing layers are stacked and arranged with a step width of 5 mm or more.

  This pneumatic tire has an advantage that the occurrence of cracks starting from the end of the rim cushion reinforcing layer is suppressed as compared with the configuration in which the end of the rim cushion reinforcing layer is in the same position.

  In the pneumatic tire according to the present invention, the rim cushion reinforcing layer is disposed over the entire circumference of the tire.

  This pneumatic tire has an advantage that the rim assembling work of the tire becomes easy because the alignment of the rim cushion reinforcing layer and the split position of the rim ring becomes unnecessary when assembling the rim of the tire.

  In the pneumatic tire according to the present invention, the rim cushion reinforcing layer is disposed only in a part in the tire circumferential direction.

  In this pneumatic tire, the rim cushion reinforcing layer may be disposed only in a part of the tire circumferential direction. In such a configuration, since the installation range of the rim cushion reinforcing layer is small, there is an advantage that the material cost of the tire is reduced.

  In the pneumatic tire according to the present invention, the width W in the tire circumferential direction of the rim cushion reinforcing layer is in a range of W ≧ 20 [mm].

  In this pneumatic tire, since the width W of the rim cushion reinforcing layer is optimized, there is an advantage that biting of the rim cushion portion at the split position of the rim ring is effectively suppressed.

  In the pneumatic tire according to the present invention, the rim cushion reinforcing layer is disposed only on one side of the tire.

  This pneumatic tire has an advantage that the material cost of the tire is reduced by arranging the rim cushion reinforcing layer only on the side surface where the rim cushion portion and the rim ring are in contact with each other on both side surfaces of the tire.

  The pneumatic tire according to the present invention includes an indicator that indicates a position of the rim cushion reinforcing layer.

  This pneumatic tire has an advantage that it is easy to align the rim cushion reinforcing layer 6 and the split position of the rim ring when assembling the tire rim.

  In addition, the pneumatic tire according to the present invention includes an end portion reinforcing layer disposed so as to cover the end portion of the carcass layer and the end portion of the carcass reinforcing layer from the outer side in the tire width direction.

  This pneumatic tire has an advantage that durability of the bead portion is ensured because the fall of the bead portion is reduced and distortion of the winding end portion of the carcass layer is suppressed.

  The pneumatic tire according to the present invention is applied to a heavy duty radial tire.

  In the heavy duty radial tire, a larger load is applied to the rim cushion portion. Therefore, there is an advantage that the effect of suppressing the deformation of the rim cushion portion can be obtained more remarkably by using such a pneumatic tire.

  In the pneumatic tire according to the present invention, since the rim cushion reinforcing layer is disposed in the region that contacts the rim flange portion in the tire rim assembly state, the rim cushion portion is reinforced. In such a configuration, the bead portion is prevented from biting into the split position of the rim ring in the tire rim assembled state. As a result, there is no need to insert a rubber sheet between the split position of the rim ring and the bead portion, and there is an advantage that deformation of the rim cushion portion is effectively suppressed. For example, in a configuration in which a rubber sheet is inserted between the rim ring split position and the bead portion in order to suppress biting of the bead portion into the rim ring split position, the distortion of the rim cushion portion increases when a load is applied. The deformation of the rim cushion part tends to be excessive. In addition, since the carcass reinforcing layer and the rim cushion reinforcing layer are respectively disposed, the rim cushion portion is effectively reinforced. Thereby, there exists an advantage by which the deformation | transformation of a rim cushion part is suppressed effectively.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  1 and 2 are a sectional view (FIG. 1) and an enlarged side view (FIG. 2) in the tire meridian direction showing a bead portion of a pneumatic tire according to an embodiment of the present invention. 3-7 is explanatory drawing which shows the modification of the pneumatic tire described in FIG. FIG. 8 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention. FIG. 9 is an explanatory diagram showing a general configuration of the rim ring.

[Pneumatic tire]
The pneumatic tire 1 includes a bead core 2, a bead filler 3, and a carcass layer 4 (see FIG. 1). The bead core 2 has an annular structure and is configured as a pair of left and right. The bead filler 3 is disposed on the outer periphery of the bead core 2 in the tire radial direction and reinforces the bead portion of the tire. The carcass layer 4 is bridged in a toroidal shape between the left and right bead cores 2 and 2 to constitute a tire skeleton. Further, both end portions of the carcass layer 4 are wound and locked outward in the tire width direction so as to wrap the bead filler 3. In this embodiment, the carcass layer 4 is composed of a steel carcass ply having a single-layer structure.

[Reinforcement layer of bead part]
Moreover, the pneumatic tire 1 has a carcass reinforcing layer 5 in a bead portion (see FIG. 1). The carcass reinforcing layer 5 is disposed at the winding portion of the carcass layer 4 to reinforce the carcass layer 4. For example, in this embodiment, the carcass reinforcing layer 5 is composed of a steel reinforcing ply having a single-layer structure. In addition, the carcass reinforcing layer 5 is laminated on the outside of the turn-up portion of the carcass layer 4 so as to wrap the bead core 2. Further, the end portion of the carcass reinforcing layer 5 on the outer side in the tire width direction and the end portion of the carcass layer 4 are arranged in the vicinity of each other and shifted in the tire radial direction in a sectional view in the tire meridian direction. The carcass reinforcing layer 5 may be disposed so as to wrap the bead core 2 from the end portion of the carcass layer 4 (see FIG. 1), or may be disposed only in the winding portion of the carcass layer 4 (illustrated). (Omitted).

  The pneumatic tire 1 has a plurality of rim cushion reinforcement layers 6 (see FIGS. 1 and 2). The rim cushion reinforcement layer 6 is disposed in a region that contacts the rim flange portion in the tire rim assembly state, and reinforces the rim cushion portion of the bead portion. For example, in this embodiment, the rim cushion reinforcing layer 6 is made of organic fiber cords such as nylon, polyester, aromatic polyamide, or metal fiber cords such as steel, and these cord materials arranged in a comb shape are covered with coat rubber. Configured. In addition, the rim cushion reinforcing layer 6 is disposed on the outer surface rubber layer (the rubber layer outside the carcass layer 4 and the carcass reinforcing layer 5) of the bead portion in the tire meridian direction in a cross-sectional view in the tire meridian direction. It extends in the tire warp direction from the bead base portion to the vicinity of the winding end portion of the carcass layer 4.

[effect]
As described above, in this pneumatic tire 1, since the rim cushion reinforcing layer 6 is disposed in the region in contact with the rim flange portion in the tire rim assembly state, the rim cushion portion is reinforced (see FIG. 1 and FIG. 1). (See FIG. 2). In such a configuration, the bead portion is prevented from biting into the split position of the rim ring 12 in the tire rim assembled state. As a result, there is no need to insert a rubber sheet between the split position of the rim ring and the bead portion, and there is an advantage that deformation of the rim cushion portion is effectively suppressed. For example, in a configuration in which a rubber sheet is inserted between the split position of the rim ring and the bead portion in order to suppress the bite portion from getting into the split position of the rim ring, the distortion of the rim cushion portion increases when a load is applied. The deformation of the rim cushion part tends to be excessive. Moreover, since the carcass reinforcing layer 5 and the rim cushion reinforcing layer 6 are respectively disposed, the rim cushion portion is effectively reinforced. Thereby, there exists an advantage by which the deformation | transformation of a rim cushion part is suppressed effectively.

  In the pneumatic tire 1, the rim cushion reinforcing layer 6 has a multilayer structure (see FIG. 1). In such a configuration, the rim cushion portion is effectively reinforced compared to the configuration in which the rim cushion reinforcing layer has a single-layer structure. Thereby, there exists an advantage by which the deformation | transformation of a rim cushion part is suppressed effectively.

[Additional matters]
For example, in this embodiment, a pair of rim cushion reinforcement layers 6 and 6 are laminated (see FIG. 1). The rim cushion reinforcement layers 6 and 6 are laminated so that the fiber directions of the cord material intersect each other (see FIG. 2). In such a configuration, the rigidity of the rim cushion reinforcing layers 6 and 6 is increased as compared with a configuration in which the rim cushion reinforcing layer is laminated with the fiber direction of the cord material oriented in the same direction. Thereby, there exists an advantage by which the bite part bite into the split position of a rim ring is suppressed effectively. In the configuration in which only the single rim cushion reinforcement layer 6 is disposed (not shown), the rim cushion reinforcement layer 6 is disposed with the fiber direction of the cord material directed in the tire circumferential direction.

  Further, in the above configuration, the fiber direction of the cord material of the rim cushion reinforcing layer 6 is 0 [deg] or more and 70 [deg] or less (and 0 [deg] or more and 40 [deg] or less) with respect to the tire circumferential direction. It is preferable to incline within the range. In such a configuration, the rigidity of the bead portion is increased by setting the inclination angle of the cord material to be low. Thereby, there exists an advantage which the durability of a bead part improves. The inclination angle of the cord material is more preferably in the range of 0 [deg] or more and 20 [deg] or less.

  In this configuration, at least two rim cushion reinforcement layers 6 and 6 on the outer side in the tire width direction (surface side of the rim cushion portion) among the plurality of laminated rim cushion reinforcement layers 6 and 6 are organic fiber materials. (See FIG. 1). In such a configuration, there is an advantage that the separation of the rubber material at the end of the rim cushion reinforcing layer is suppressed as compared with the configuration in which the rim cushion reinforcing layer on the outer side in the tire width direction is made of a steel fiber material.

  For example, in this embodiment, a pair of rim cushion reinforcement layers 6 and 6 are disposed, and both are made of an organic fiber material (see FIG. 1). Further, for example, in a configuration in which three rim cushion reinforcing layers 6 are laminated (see FIG. 3), two layers on the outer side in the tire width direction are made of organic fiber material, and one layer on the inner side in the tire width direction is steel. It is composed of a fiber material.

  Moreover, in this pneumatic tire 1, it is preferable that the rim cushion reinforcement layer 6 is coat | covered with a coat rubber material, and the JIS-A hardness (JIS-K6253 conformity) of this coat rubber material exists in the range of 60-95. Thereby, since the hardness of the rim cushion reinforcement layer 6 is ensured, there is an advantage that the bead portion bites into the split position of the rim ring 12 in the tire rim assembled state is effectively suppressed.

  In addition, an intersection B between the perpendicular drawn from the center of gravity of the bead core 2 in the tire radial direction and the bead base portion is taken in a sectional view in the tire meridian direction. At this time, in the pneumatic tire 1, the distance H in the tire radial direction from the intersection B to the outer end in the tire radial direction of the rim cushion reinforcing layer 6 and the separation point between the rim and the tire at the time of load application from the intersection B. The distance RH preferably has a relationship of 1.0 ≦ H / RH ≦ 1.5 (see FIG. 1). In such a configuration, since the positional relationship H / RH between the end of the rim cushion reinforcing layer 6 on the outer side in the tire radial direction and the rim and the separation point of the tire is optimized, the split position of the rim ring 12 in the rim assembled state of the tire There is an advantage that biting of the bead portion into the head is effectively suppressed. For example, when H / RH <1.0, the rim cushion reinforcement layer is located on the inner side in the tire radial direction from the separation point, so that the bead portion bites into the split position of the rim ring during overloading or use at low air pressure. It is easy to generate.

  The separation point between the rim and the tire is that the pneumatic tire 1 is assembled to a rim defined by the Chinese National Standard (GB standard), and the single maximum load and air pressure defined by the pneumatic tire 1 are applied to the tire. Measured under load.

  Further, in this pneumatic tire 1, the end portion on the inner side in the tire radial direction of the rim cushion reinforcing layer 6 is in the vicinity of the inner end portion in the tire radial direction of another reinforcing layer (carcass reinforcing layer 5) disposed in the bead portion. It is preferable (see FIG. 1). Here, the “vicinity” of the inner end portion in the tire radial direction means a range within ± 5 [mm]. In such a configuration, the position of the end portion on the inner side in the tire radial direction of the rim cushion reinforcing layer 6 is optimized, so that the occurrence of cracks starting from the end portion on the inner side in the tire radial direction of the rim cushion reinforcing layer 6 is suppressed. There are advantages. For example, in this embodiment, the distance H ′ in the tire radial direction from the bead base portion to the end portion on the inner side in the tire radial direction of the rim cushion reinforcing layer 6 is greater than the end portion on the inner side in the tire radial direction of the carcass reinforcing layer 5. Arranged radially outside.

  Moreover, in this pneumatic tire 1, it is preferable that at least a pair of rim cushion reinforcement layers 6 and 6 are laminated and arranged with step widths S1 and S2 of 5 [mm] or more separated (see FIG. 4). That is, the end portions of the rim cushion reinforcing layers 6 and 6 are arranged with a predetermined step width S1 and S2 shifted. In such a configuration, there is an advantage that the occurrence of cracks starting from the end of the rim cushion reinforcing layer is suppressed as compared with the configuration in which the end of the rim cushion reinforcing layer is in the same position.

  Moreover, in this pneumatic tire 1, it is preferable that the rim cushion reinforcement layer 6 is arrange | positioned over the tire perimeter (refer FIG. 2 and FIG. 5). Such a configuration has an advantage that the rim assembling work of the tire becomes easy because the alignment of the rim cushion reinforcing layer 6 and the split position of the rim ring 12 is not required when assembling the rim of the tire.

  However, the present invention is not limited to this, and the rim cushion reinforcing layer 6 may be disposed only in a part in the tire circumferential direction (see FIG. 6). In such a configuration, since the installation range of the rim cushion reinforcing layer 6 is small, there is an advantage that the material cost of the tire is reduced.

  Moreover, in said structure, it is preferable that the width W of the tire circumferential direction of the rim cushion reinforcement layer 6 exists in the range of W> = 20 [mm] (refer FIG. 7). In such a configuration, since the width W of the rim cushion reinforcing layer 6 is optimized, there is an advantage that biting of the rim cushion portion at the split position of the rim ring 12 is effectively suppressed.

  Moreover, in this pneumatic tire 1, it is preferable that the rim cushion reinforcement layer 6 is disposed only on one tire side. In such a configuration, the rim cushion reinforcing layer 6 is disposed only on the side surface where the rim cushion portion and the rim ring 12 are in contact with each other on the both side surfaces of the tire, thereby advantageously reducing the material cost of the tire. In addition, the rim cushion reinforcing layer 6 may be disposed on both side surfaces of the tire.

  The pneumatic tire 1 preferably has an indicator that indicates the position of the rim cushion reinforcing layer 6 (not shown). With such a configuration, there is an advantage that alignment between the rim cushion reinforcing layer 6 and the split position of the rim ring 12 becomes easy when assembling the tire rim. In addition, the structure which changed the color of the rubber material partially, the structure which formed the unevenness | corrugation in the surface of a rim cushion part, etc. may be employ | adopted for an indicator.

  Moreover, it is preferable that this pneumatic tire 1 has the edge part reinforcement layer 7 in a bead part (refer FIG. 1). The end portion reinforcing layer 7 is disposed so as to cover the end portion of the carcass layer 4 and the end portion of the carcass reinforcing layer 5 from the outer side in the tire width direction, and reinforces the bead portion. For example, in this embodiment, the carcass reinforcing layer 5 is laminated on the winding portion of the carcass layer 4, and these are wound back outward in the tire width direction so as to wrap the bead core 2 and the bead filler 3. At this time, the end portion reinforcing layer 7 is disposed outside the bead filler 3 in the tire width direction so as to cover both the end portion of the carcass layer 4 and the end portion of the carcass reinforcing layer 5. The end reinforcing layer 7 is made of steel and has a multilayer structure (see FIG. 1). For example, in this embodiment, the pair of end portion reinforcing layers 7 and 7 are stacked and arranged. Further, the end reinforcing layer 7 is disposed between the carcass reinforcing layer 5 and the rim cushion reinforcing layer 6 in a sectional view in the tire meridian direction.

  In such a configuration, the end reinforcing layer 7 is disposed so as to cover the end of the carcass layer 4 and the end of the carcass reinforcing layer 5 from the outer side in the tire width direction, so that the fall of the bead portion is reduced (see FIG. 1). ). Thereby, since the distortion | strain of the winding end part of the carcass layer 4 is suppressed, there exists an advantage by which the durability of a bead part is ensured. In particular, in the configuration having the rim cushion reinforcing layer 6 and the end reinforcing layer 7, the rigidity of the bead portion is ensured by these synergistic effects. Thereby, there exists an advantage by which the deformation | transformation of a rim cushion part is suppressed effectively.

  The pneumatic tire 1 is preferably a heavy duty radial tire. In such a pneumatic tire, a larger load is applied to the rim cushion portion. Therefore, there is an advantage that the effect of suppressing the deformation of the rim cushion portion can be obtained more remarkably by using such a pneumatic tire.

[performance test]
In this example, a performance test on the amount of deformation of the rim cushion portion was performed for a plurality of pneumatic tires having different conditions (see FIG. 9). In this performance test, a pneumatic tire having a tire size of 1100R20 is assembled to a rim having a rim size of 20 × 8.00V and mounted on a test vehicle that is a 2-D truck. The pneumatic tire is loaded with an air pressure of 830 [kPa] and a single maximum load of the Chinese national standard (GB standard). And the deformation | transformation amount of a rim cushion part is observed after 6-month driving | running | working by a market monitor. If the deformation amount of the rim cushion portion is less than 3 [mm], it is determined that the rim cushion portion is at an acceptable level. Moreover, the presence or absence of the generation | occurrence | production of the crack in the edge part of a rim cushion reinforcement layer is observed.

  In the pneumatic tires of Conventional Example 1 and Conventional Example 2, the end portion of the carcass layer is wound back to the outer side in the tire width direction so as to wrap the bead core. Moreover, the carcass reinforcement layer which is arrange | positioned at the winding | wrapping part of a carcass layer and reinforces a carcass layer is provided. In the pneumatic tire of Conventional Example 2, a rubber sheet is sandwiched between the rim cushion portion and the split position of the rim ring. This suppresses the bead portion from biting into the split position of the rim ring.

  On the other hand, in the pneumatic tire 1 of Invention Examples 1 to 8, in addition to the configuration of the pneumatic tire of the conventional example, the rim cushion portion is reinforced by being arranged in a region contacting the rim flange portion in the tire rim assembled state. A rim cushion reinforcing layer 6 is provided (see FIGS. 1 and 2).

  As shown in the test results, it can be seen that in the pneumatic tires 1 of Invention Examples 1 to 8, the amount of deformation of the rim cushion portion is reduced (see FIG. 8). Further, when Invention Example 1 and Invention Example 2 are compared, the amount of deformation of the rim cushion portion is further reduced because the rim cushion reinforcement layers 6 and 6 are laminated with the fiber directions of the cord material intersecting each other. I understand that. In addition, when Invention Examples 2 to 4 are compared, the amount of deformation of the rim cushion portion is effectively reduced by optimizing the inclination angle of the cord material of the rim cushion reinforcing layer 6 with respect to the tire circumferential direction. I understand. Further, when Invention Example 1 and Invention Example 5 are compared, the positional relationship H / RH between the end portion of the rim cushion reinforcing layer 6 on the outer side in the tire radial direction and the rim and the separation point of the tire is optimized. It can be seen that the amount of deformation of the cushion portion is effectively reduced. Further, when Invention Example 1 and Invention Example 6 are compared, it can be seen that the deformation amount of the rim cushion portion is further reduced by further disposing the rim cushion reinforcement layer 6 made of a steel fiber material. In Invention Example 6, the rim cushion reinforcing layer 6 made of one steel fiber material is arranged on the inner side in the tire width direction, and the rim cushion reinforcing layer 6 made of two organic fiber materials is arranged on the outer side in the tire width direction. (See FIG. 3). Further, when Invention Example 7 and Invention Example 8 are compared, when the rim cushion reinforcement layer 6 is disposed only in a part in the tire circumferential direction, the width W in the tire circumferential direction of the rim cushion reinforcement layer 6 is optimized. It can be seen that the amount of deformation of the rim cushion portion is effectively reduced.

  As described above, the pneumatic tire according to the present invention is useful in that it can suppress biting of the bead portion into the split position of the rim ring and deformation of the rim cushion portion.

It is sectional drawing of the tire meridian direction which shows the bead part of the pneumatic tire concerning the Example of this invention. It is an enlarged side view which shows the bead part of the pneumatic tire concerning the Example of this invention. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is a graph which shows the result of the performance test of the pneumatic tire concerning the Example of this invention. It is explanatory drawing which shows the general structure of a rim ring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Bead core 3 Bead filler 4 Carcass layer 5 Carcass reinforcement layer 6 Rim cushion reinforcement layer 7 End part reinforcement layer 10 Rim 11 Rim body 12 Rim ring

Claims (14)

A pneumatic tire comprising a pair of bead cores and a carcass layer spanned between these bead cores, and an end portion of the carcass layer is rolled back outward in the tire width direction to wrap around the bead core,
A carcass reinforcing layer that is disposed at the turn-up portion of the carcass layer and reinforces the carcass layer, and a plurality of rim cushion reinforcements that are disposed in a region that contacts the rim flange portion in a tire rim assembled state and reinforces the rim cushion portion And a pneumatic tire.   2. The pneumatic tire according to claim 1, wherein the rim cushion reinforcement layer is made of a cord material in which the rim cushion reinforcement layers are arranged, and the plurality of rim cushion reinforcement layers are laminated so that fiber directions of the cord material intersect each other.   The pneumatic tire according to claim 1 or 2, wherein the fiber direction of the cord material of the laminated rim cushion reinforcement layer is inclined within a range of 0 [deg] or more and 40 [deg] or less with respect to the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 3, wherein at least two rim cushion reinforcement layers on the outer side in the tire width direction are made of an organic fiber material among the plurality of laminated rim cushion reinforcement layers. When taking the intersection B between the perpendicular line drawn from the center of gravity of the bead core in the tire radial direction and the bead base portion in a cross-sectional view in the tire meridian direction,
The distance H in the tire radial direction from the intersection point B to the outer end in the tire radial direction of the rim cushion reinforcement layer and the distance RH from the intersection point B to the rim and tire separation point when loaded are 1.0 ≦ H. The pneumatic tire according to claim 1, having a relationship of /RH≦1.5.   The tire radial direction inner side edge part of the said rim cushion reinforcement layer exists in the vicinity of the tire radial direction inner side edge part of the other reinforcement layer arrange | positioned at the bead part. Pneumatic tires.   The pneumatic tire according to any one of claims 1 to 6, wherein at least a pair of the rim cushion reinforcing layers are disposed so as to be stacked with a step width of 5 mm or more.   The pneumatic tire according to any one of claims 1 to 7, wherein the rim cushion reinforcing layer is disposed over the entire circumference of the tire.   The pneumatic tire according to any one of claims 1 to 7, wherein the rim cushion reinforcing layer is disposed only in a part of the tire circumferential direction.   The pneumatic tire according to claim 9, wherein a width W in a tire circumferential direction of the rim cushion reinforcing layer is in a range of W ≧ 20 [mm].   The pneumatic tire according to any one of claims 1 to 9, wherein the rim cushion reinforcing layer is disposed only on one tire side.   The pneumatic tire according to any one of claims 1 to 11, further comprising an indicator that indicates a position of the rim cushion reinforcing layer.   The pneumatic tire according to any one of claims 1 to 12, further comprising an end portion reinforcing layer disposed so as to cover an end portion of the carcass layer and an end portion of the carcass reinforcing layer from the outer side in the tire width direction.   The pneumatic tire according to claim 1, which is applied to a heavy duty radial tire.

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